Peters



R. B. DONALD'SON. Support for De ntal Mouth-Glasses;

No. 224,663. Patented Feb..17, 1880.

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, UNITED STATES PATENT OFFICE;

ROBERT B. DONALDSON, OF WASHINGTON, DISTRICT or COLUMBIA.

SUPPORT FOR DENTAL MOUTH-GLASSES.

SPECIFICATION formingpart of Letters Patent No. 224,6 3, dated February17, 1880.

Application filed January 21, 1880.

To all whom it may concern: I

Be it known that T, ROBERT B. DONALDSON, a citizen of the United States,residing at l/Vashington, in the District of Columbia, have inventedcertain new and useful Improvements in Supports for DentalMirror-Glasses; and I do hereby declare the following to be a full,clear, and exact description of the invention,

such as will enable others skilled in the art to which it appertains tomake and use the same, reference being had to the accompanying drawings,and to letters or figures of reference marked thereon, which form a partof this specification.

My invention relates to an arm or support of peculiar constructioncombined with and adapted to serve in relation to a mouth-mirror of thekind usually employed in dental surgery.

In this art it has heretofore been customary for the operator to holdthe month-mirror in one hand, and to thus change the position of thesame as occasion required, to throw the gathered rays of light againstthe portions or cavities of the teeth being treated, or expose to theoperator, by reflection, such parts. This practice, as is obvious, notonly greatly reduced the dentistscapacity for useful and efficientservice, in consequence of the fatigue and nervousness caused by eithera constrained or cramped position or the length of time necessarilyconsumed in the operation, one hand being wholly or partially employedin holding the glass.

My invention is designed to overcome these difficulties; and to this endI provide a device adapted to be secured to the dental chair or otherconvenient place, the object of which is to provide for expeditious,ready, and rapid adjustment of the mirror to any and the precise anglerequired to expose the tooth or teeth being operated upon.

This invention also, in addition to its easy and rapid adjustment,provides for its equally easy and rapid withdrawal and its'retentionwithin easy reach of the operator when required for further use,avoiding all danger of its being mislaid, lost, or out of convenientreach.

My invention consists, chiefly, in a standard, preferably adjustable, aflexible or differentially-jointed arm pivoted thereto, said armcarrying a mirror or other reflecting or magnifying device, swiveled orotherwise secured thereto upon its free end, as will be more fullyhereinafter set forth.

The standard is adapted to be secured to the dental chair, preferably tothe head-rest thereof, or other convenient fixed or movable object, andthe portion carrying the arm is preferably adapted for adjustment.

In what I consider the best manner of carrying out my invention, Iemploy an arm formed of several short links or joints, each providedatone end with a transverse slot or mortise, the sides of which areperforated to receive a pivotal pin, and at the other end with acorresponding tenon. The mortise of one joint receives the tenon of theadjacent joint, and in this manner the arm may be made of any desirablelength, according to the number of joints or sections employed. Thesetenons and mortises are arranged differentially, so as to have a planeof action in many directions, and allowing the arm or support to be bentor curved at will. The inortises in the longer sections are slitted topermit of spring at those points in connection with set-screws.

In the accompanying drawings, Figure 1 is a perspective view of myinvention; and Figs. 2, 3, 4, 5, and 6 are details.

Referring to the drawings, A represents the standard, 13 the flexiblearm, and G the mirror.

The arm, as shown, is formed of sections or joints pivoteddifferentially together by tenonand-mortise joint. For convenience Iwill describe one of these joints, 1), it being understood that the armB is formed by the articulation of several. The sections b may be of thesame or difierent lengths, each beingprovided with a mortise or ope-nslot upon one end, as shown at b, and transverse perforations 1), and atthe opposite end with a tenon, b perforated at If. These perforationsreceive the pivotal'pins. As these joints must have a plane of action indifferent directions, and a proper amount of friction must be providedat each articulation to allow the joints to retain the various shapes ofwhich it is capable under the manipulation of the operator,

I form the shoulder at one end of each section with a concave surface,I), and provide a convex surface, b at the opposite end, to corre spondand operate therewith, or vice versa.

The mirror 0 is preferably swiveled at the free end in any convenient ordesirable manner. The mirror 0 is shown swiveled in the end section byan arm inserted into a socket in said end section, which socket isslitted to give a spring-pressure upon the arm, thus affordin g therequisite friction in the movements of the glass. If desired, aset-screw can be employed to bear on the arm, by means of which thejoint could be tightened at pleasure.

From the foregoing description the operation of the device is obvious.

Various modifications may be made without departing from the principleof my invention, the essential features of which are a flexible ordifferentially-jointed adjustable arm or support and a mirror combinedand adapted to operate together as and for the purposes set forth.

I am aware that jointed cables have been made for other purposes of aconstruction somewhat similar to mine, except that they have nofrictional bearings to hold the parts in any required position.

I am also aware that jointed arms have been in use for holdingdressing-mirrors in position; but these have required set-screws, whichhave to be tightened in order to retain the arm in the requiredposition, and are not so constructed as to be held by the friction ofthe joints, as mine is.

I am also aware that a plain copper wire has been used as a flexiblesupport for lamps and for microscopic rests; but it is evident that awire, when used as a flexible support, will soon weaken and break ifoften bent and rebent, as would have to be the case if used inconnection with a dental mirror or for analogous purposes; besides whicha wire of sufficient size to give the requisite rigidity'and prevent thevibration of the glass would be much too st-iif to admit of readyadjustment.

Having thus fully described my invention, what I claim, and desire tosecure by Letters Patent, is-

1. The differei'itially-j ointed and flexible arm with opposite concaveand convex shoulders at the joints to produce friction and rigidity forholding automatically the arm at any point to which it may be adjusted,all arranged as described, and adapted for use with a mouthmirror orother analogous device.

2. The flexible cable, as described, capable of automatic adjustment andfrictional retention at any desired point, in combination with amouth-mirror swiveled by its shank in the spring-jaws which form a partof or are attached to the nearest joint of the cable, all as and forthepurposes set forth.

In testimony whereof I aflix my signature in presence of two witnesses.

ROBERT B. DONALDSON.

Witnesses J AS. H. LANGE, H. M. ScHooLEY.

